This build of powder works fine from Sudokuhax on DSi - misplaced my Sudokuhaxxed 3DS atm but there's no reason why it shouldn't work.
Pretty much all DS homebrew should work fine in DSi mode if it's compiled with the latest tools & libraries - if that's actually possible, unfortunately there were some things that will need a complete rewrite.
Pretty much all DS homebrew should work fine in DSi mode if it's compiled with the latest tools & libraries - if that's actually possible, unfortunately there were some things that will need a complete rewrite.